Ibrutinib is more effective without dose interruptions in CLL
This study looked at the effect of interruptions to daily ibrutinib (Imbruvica) treatment in patients with chronic lymphocytic leukemia. This study concluded that interruptions can have negative effects on patient outcomes.
Chronic lymphocytic leukemia (CLL) is a cancer that affects the lymphocytes (a type of white blood cell). Ibrutinib is a common treatment for CLL combined with chemotherapy. Ibrutinib is a Bruton’s tyrosine kinase inhibitor. This treatment blocks the effects of a protein involved in cancer cell growth.
Some patients may need to take breaks from treatment due to side effects. The effects of ibrutinib wear off quickly when treatment is stopped. Cancer cells begin growing again. However, the effects of treatment interruptions on outcome are not known.
This study involved 195 patients with CLL or a similar form of lymphoma (SLL). All patients were treated with ibrutinib once daily by mouth over a 9 month period. Patients were followed for up to an average of 30.4 months.
Those taking a higher dose (420 mg) of ibrutinib had longer progression-free survival (time from treatment until disease progression) than those taking a lower dose (140-280 mg). This was not affected by whether patients had certain genetic changes (del17p and TP53) or not. Patient weight or age also did not interfere with treatment. Patients treated with a higher dose had a 94% 12-month overall survival rate (time from treatment until death from any cause). This was compared to 75% for those treated with a lower dose.
79 patients needed to stop treatment due to adverse events. Treatment was stopped for an average of 18.7 days (range 8-56 days). The effectiveness of treatment was significantly reduced when patients missed more than 8 days in a row. Progression-free survival was significantly lower in those missing more than 8 days in a row.